Gustay selle



NrrED STATES ATENT GUSTAV SELLE, OF BRANDENBURG, GERMANY.

SPECIFICATION forming part of Letters Patent No. 604,269, dated May 1'7, 1898.

Application filed Ap 29, 1895. Serial No. 547,539. (No specimens.)

To all whom it may concern: 7

Be it known that I, GUSTAV SELLE, a subject of the German Emperor, and a resident of Brandenburg-on-the-Havel, in the Empire of Germany, have invented certain new and useful Improvements in the Production of Photographs in Natural Colors, of which the following is a specification.

This invention relates to the production, by superposition of three differently colored transparencies, of a colored photograph in natural colors; and its object is to produce such photograph in an easier and more perfect manner than heretofore. In previous attempts in this direction gelatin films colored With insoluble pigment have been exposed under negatives and developed in hot water by which parts of the gelatin are dissolved away, carrying away with them the insoluble pigment from such places. This proc-- ess not only produces a transparency in relief which is difficult to superpose, but also is liable to distortion, so that the colored photographs do not come into exact coincidence and the desired effect is not obtained. In such process also the supports for the gelatin have been used temporarily only, partly with the view to be able to bring the gelatin films into absolute contact, partly since such supports were of a thickness which would quite prevent such near approach of the gelatin or actual picture-bearing films as is necessary to obtain the effect of natural colors in the combined photograph. The removal of the support, however, as aforesaid, without distortion of the film is of supreme difiiculty. By the present invention these difficulties are overcome or avoided partly by the use of extremely thin collodion films for more immediately carrying the gelatin film, such collodion films being during the development process themselves carried by a support such as a glass plate partly by avoiding the hot-waterdevelopment process and insoluble pigment, which leaves the gelatin film in relief, and consequently requires a comparative thickness of film, and using in place thereof a soluble mordant in the gelatin and a cold-wa ter process of development and subsequent dyeing, which leaves the gelatin film quite smooth and of even thickness throughout and allows of a thinner gelatin film. Thus by the use of the collodion under layer these films when stripped from the glass are not liable to distortion and are still, including the permanent collodion layer, of such thinness that when superposed they are close enough together to give the natural effect of the color of the objects represented in the photograph.

Such process is carried out as follows: An excessively thin coating of collodion is spread on a glass plate, and when dry the chromated gelatin emulsion is spread thereon. Three such plates are exposed to light beneath three negatives which have been respectively taken of the same object with interposition of three different-colored light-filters. The faces of the plates are next to the negatives. Each plate is then immersed in a bath of cold water in which a soluble dye has been dissolved complementary to the color of the respective lightfilter which was used in the production of the corresponding negative. The previously clear and colorless gelatin takes up the dye at such places as the light has acted upon, but none of the gelatin is dissolved. IVhen dry, the gelatin films,with their collodion under layer adhering to them, are stripped from the glass and the three thus-produced transparencies are superposed and suitably mounted or attached.

I do not claim as my invention the use, broadly, of a film-carrier nor the production of natural-colored photographs from three differentlycolored superposed transparencies, nor do I claim the use of pigmented gelatin; but

What I claim is- The process for the production of naturalcolored photographs from three negatives, taken with interposition respectively of three differently-colored light-filters, consisting in forming three plates by spreading upon a firm support an excessively thin adhering coating of collodion and upon the latter an adhering coating of colorless chromated gelatin emulsion, exposing the plates so formed respectively behind the negatives with the gelatin coating in contact With the negative, immersing each plate in cold Water containing a dye or solution complementary to the color of the light-filter used for the corresponding negative, subsequently detaching the collodion films with the gelatin films thereon from the supports and superposing said detached films. 10

In Witness whereof I have signed this specification in presence of two witnesses.

GUSTAV SELLE. Witnesses: 7

WM. HAUPT, CHAs. KRUGER. 

